io_uring/fdinfo: fix OOB read in SQE_MIXED wrap check

{
  "id": "7a0d90de96449e2c109818d6e94c410fecbe08b368d3c74c485ca2a0997ab325",
  "url": "https://osv.dev/vulnerability/CVE-2026-31484",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "io_uring/fdinfo: fix OOB read in SQE_MIXED wrap check",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: io_uring/fdinfo: fix OOB read in SQE_MIXED wrap check __io_uring_show_fdinfo() iterates over pending SQEs and, for 128-byte SQEs on an IORING_SETUP_SQE_MIXED ring, needs to detect when the second half of the SQE would be past the end of the sq_sqes array. The current check tests (++sq_head & sq_mask) == 0, but sq_head is only incremented when a 128-byte SQE is encountered, not on every iteration. The actual array index is sq_idx = (i + sq_head) & sq_mask, which can be sq_mask (the last slot) while the wrap check passes. Fix by checking sq_idx directly. Keep the sq_head increment so the loop still skips the second half of the 128-byte SQE on the next iteration.",
    "evidence": "osv:CVE-2026-31484",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.19.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-31484",
      "aliases": [
        "CVE-2026-31484"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "1cba30bf9fdd6c982708f3587f609a30c370d889"
                },
                {
                  "fixed": "ba21ab247a5be5382da7464b95afbe5f0e9aa503"
                },
                {
                  "fixed": "5170efd9c344c68a8075dcb8ed38d3f8a60e7ed4"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-31484.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "6.19.11"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-31484.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.768877360Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/5170efd9c344c68a8075dcb8ed38d3f8a60e7ed4",
        "https://git.kernel.org/stable/c/ba21ab247a5be5382da7464b95afbe5f0e9aa503",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31484.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-31484",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31484.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-31484",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 491316,
  "published_at": "2026-04-22T13:54:10.223+00:00"
}